1. Field of the Invention
The present invention relates to amphibious vehicles, particularly to adaptations thereto for making the hulls of such vehicles water-resistant or water-tight.
2. Related Art
Amphibious vehicles, originally designed for military use, have become popular vehicles for sight-seeing tours and other civilian purposes. The vehicles, the bottoms of which comprise a buoyant hull, contain both wheels for land use as well as a propeller for water use. Given the heavy use that many such vehicles receive and the amount of time the vehicles are in the water, adaptations to make them less water-permeable will serve to improve safety and reliability, reducing the amount of time such vehicles must be taken out of service for repairs.
To protect it from the effects of water, the engines of such vehicles are situated inside of the hull. On the other hand the propeller and wheels must be situated outside of the hull. There must therefore be at least one penetration of the hull to transfer the power of the engine, via a drive shaft, to the wheels and propeller. This penetration, which in some cases is in an arched indentation in the underside of the hull, must be sealed in a water-tight connection to prevent the vehicle from taking on water. However, while remaining water-tight the connection must also permit movement of the drive shaft relative to the hull. In some amphibious vehicles there is a greased bearing through which the drive shaft penetrates the hull, and this bearing alone is what seals the hull. Nonetheless, considering that this bearing is exposed to hydrostatic pressure such a bearing can fail, leading to unchecked flooding of the hull.
Many amphibious vehicles that were built long ago for military use are still in service for civilian purposes. Many retrofitted improvements to the original design are added to the vehicles to improve the vehicles' safety and performance, which is important in light of the heavy use the vehicles receive.
Thus what is needed is an apparatus which permits penetration of one or more rotating shaft assemblies through the hull in a way that maintains a water-tight connection while permitting rotation of the shafts, and a method of retrofitting existing amphibious vehicles to accommodate this apparatus. This method and apparatus should protect the bearings from direct contact with water while also providing backup leakage protection in case of failure of any penetration points.